They have two other things in common. Both are 32, and each finished Wimbledon in tears.

It's tough to win a Slam after 30. Each year the body grows more weary, and the age gap between opponents widens. Meanwhile, the competition creeps closer.

Federer, Williams and Li Na have all won Slams in their 30s. Yet their triumphs skew the evidence. According to an analysis conducted by Nate Silver's FiveThirtyEight, only 10.3 percent of majors have been won by someone older than 29 and just 3.3 percent by a player over 31.

Many players compete after they turn 30. Yet there are so few early '80s babies winning Slams.

FiveThirtyEight analyzed the likelihood of players winning a Slam after age 30. It's unlikely.

John McEnroe and Bjorn Borg were only 25 when they won their last Slam. Mats Wilander won all seven of his Slams by age 24.

If you only include retired players, the mean age of a Slam winner is 25.16. Jimmy Connors reached a semifinal at the U.S. Open at age 39, but he was 31 when he won his last Slam.

Among the Top 25 on the WTA and ATP Tours, six women and six men are 30 or older.

Of course, anyone who enters a Slam has a chance to win it. However, most of the players over 30 are long shots.

Only a select few, nearly all already Slam winners, have any serious shot at pulling it off.

Roger Federer

Federer pushed Novak Djokovic to five sets in the Wimbledon final. However, Djokovic controlled most of the match. Federer poured every ounce of his heart and soul into winning. He still came up short.

The tear running down his right cheek signified how much emotional and physical effort goes into winning a Slam.

Many considered Wimbledon Federer's best and, perhaps, last chance to win a Slam. He's won Wimbledon seven times. Next year there will be three weeks instead of two between the French Open and Wimbledon. The additional week could provide Federer with enough reserves to get that win.

Li Na

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Li Na poses with the 2014 Australian Open trophy.Graham Denholm/Getty Images

Age: 32

Best Chance at a Slam: Australian Open

Perhaps because she considers it her "home Slam," Li performs better in Melbourne than she does at any other Slam. She won this year, and last year she reached the final. Li could also win at the U.S. Open. She's quick, takes the ball early and is unafraid to charge the net.

David Ferrer

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David Ferrer eyes the ball during a Wimbledon match.Jan Kruger/Getty Images

Age: 32

Best Chance at a Slam: French Open

David Ferrer is arguably the best clay-court specialist to never have won a French Open. He reached the final in 2013. His career winning percentage on clay is 71.6.

Ferrer has been so close. He remains consistent and doesn't appear to have suffered a major drop-off in intensity or stamina. Things would have to break his way. Top seeds, especially Rafael Nadal, would need to get nixed in earlier rounds.

Venus Williams

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Venus Williams prepares to hit a backhand volley during a third-round match at Wimbledon.Sang Tan/Associated Press

Age: 34

Best Chance at a Slam: Wimbledon

Venus Williams was two points away from sending Wimbledon champion Petra Kvitova home in the third round. Considered the best match of the women's tournament, the three-setter featured two grass-court champions.

After the loss, Williams told The Guardian about how tough it is to win a Slam: "No one gives it to you. They snatch it away and say: ‘mine.’ That’s what I’ll have to do. Snatch it, say, ‘mine’, too, growl if need be. That’s what it takes.”

Winning another Slam will be difficult for Williams. However, the way she battled Kvitova, the same woman who crushed Eugenie Bouchard in the final, proves Williams just might have another Wimbledon title in her.

He reached the fourth round at the U.S. Open last year. A bigger long shot than Venus Williams, Hewitt could sneak through a favorable draw and win the U.S. Open. If he ever reached the final of the Australian Open, enthusiastic Aussie fans could propel him to victory.

Serena Williams

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Serena Williams reaches to make a play on the ball during a Wimbledon match.Al Bello/Getty Images

Age: 32

Best Chance at a Slam: U.S. Open

Winning a Slam seemed inevitable when Williams began this season. But she's yet to move beyond the fourth round at a major.

Still, of all the players in the over-30 crowd, Williams is the most likely to win another Slam. Even if she fails to win the U.S. Open, she probably has enough in the tank to win two more Slams. Much will depend on her health and whether her heart is in it.